Waxed wrapper



Patented Dec. l2, 1933 UNITED STATES PATENT OFFICE Nashua Gummed &

Coated Paper Company,

Nashua, N. H., a corporation of Massachusetts Application December 4, 1931. Serial No. 579,037

18 Claims.

This invention relates tc waxed wrappings for commodities, and the object is to provide an improved type of wrapping of equal or greater einciency than those hitherto known with respect to resistance to moisture and other physical properties but which will provide a more effective and attractivepackage. This application is a continuation in part of my application Serial No. 541,111, led May 29, 1931.

Waxed wrappers are extensively used at the present time in wrapping bread and for convenience in the following description bread will Vbe specifically referred to as the commodity wrapped, but this is not to be understood as a limitation of the scope of the invention.

The invention will be well understood by reference to the following description of an illustrative embodiment thereof taken in connection with the accompanying drawing, wherein:

Fig. 1 is a perspective of a wrapped loaf of bread;

Fig. 2 is a diagram illustrating, although in an entirely unrealistic manner, the production of the Wrapping; and

Fig 3 is a diagrammatic section through the improved form of wrapping material.

For convenience the practice in wrapping bread prior to this invention will be described to facilitate the understanding of the objections thereto and the improvements arising from the present invention. The wrapper is made of a light, yet strong, ble ached sulphite stock which is treated with colorless paraffin wax. Some letter-press or decoration ls associated therewith in order to identify the product, usually by printing it on the paper before waxing. The waxed wrapper is applied to the loaf, usually by means of a machine, and sealed in position by a localized melting of the wax which causes the overlapping parts to cohere, It may be noted that colorless wax is imperative since some of it may be transferred, particularly by this sealing process, to the loaf of bread itself, and while colored wax might be harmless its conspicuous presence on the loaf appealed to' the purchasing public as a protection to the loaf. Their appearance, however, has not been particularly attractive. The general color eifect is dull. There is little gloss and the printed matter is not' effectively displayed. Even when this utilized inks as different as blue and red, the contrasts in value and chroma were poor. Even the high value of the original white paper was objection has been that in wrapping the loaf the waxed paper was always to some extent irregularly crumped, fracturing the wax nlm. These pfracture lines showed white on the inished package and detracted from its appearance. Where the wrappers were sealed at the ends and bottom by melting of the wax, the wax was redistributed at those locations in the paper and the appearance along the seal was different from that of the mainl body of the wrapper, detracting from the appearance of the wrapper as a whole.

By the use of the wrapper of the present invention these criticisms are obviated. A Wrapper of high gloss is provided which eiectively displays colored matter printed thereon or other; wise associated therewith. This is effected .by providing a. novel waxed wrapping sufciently thin or light in weight to be commercially feasible, at the same time of such thickness and strength as to be adaptable as a wrapping, especially when applied by machine, and which is nevertheless substantially opaque so that the chromatic effect to the eye is not substantially impaired by the color of the enclosed commodity. It has a-high gloss, particularly when the body color is white, and displays with strong contrast adjacent color either associated therewith or printed thereon. In the latter case it might be said to provide for associating with the commodity a brilliant display or advertisement eiectively carried by a wrapper, and in particular by a waxed and moisture-resist* ing wrapper, so that both can be handled and applied as a single sheet.

Waxed wrapping papers as hitherto known have been to a considerable degree transparent even although the body stock before waxing was substantially opaque. The reason for this is that a sheet of paper consists of a mat of interlaced fibers of cellulose which in themselves are.

practically transparent. This property of cellulose is practically utilized ln the arts in the provision of wrappings of regenerated cellulose, popularly known by such commercial names as Cellophane and the like, which are in general use on commodities where a clear transparent wrapping is desirable,l these sheets being of a glass-like transparency; Paper, on the contrary, appears opaque because it is non-homogeneous. The presence of innumerable air bubblesI and the entangled position of the fibers and ilbrlllae ren- 2 ders thesheet asa whole optically anisotropic and the light-is so reflected and refracted that `little istransmitted'. When, however, the paper is extent excluded by impregnation, the resultant composite sheet of cellulose fiber and parailin is substantially isotropic and a high degree of transparency results. Ii air could be wholly excluded.

- which is commercially impossible, andV if the parailln could be made to crystallize on cooling with perfect homogeneity, which is also commercially impossible, the degree of transparency obtained would be very high indeed and would compare with that of the regenerated cellulose referred to..v

Whena waxed wrapper as hitherto known is used, therefore, much of the incident light is not reflected therefrom. On the contrary, the brown bread is seen through the wrapper toning down toward uniformity any colors associated therewith.

f I` will rst describe didactically one practical form of wra per (without limitation thereto) and then explai our theoretical understanding of the causes as I now can see them for the improved results which I have empirically demonstrated. To provide a wrapper in accordance with the present invention a base paper stock may be utilized having associated therewith material having a relatively high refractive index so that the resulting sheet is anisotropic and, when its thickness and physical structure are considered, may be properly called substantially opaque. While by utilization of suitable refractive materials as suggested below such material may be incorporated in the body of the sheet without unduly loading and weakening it, it is` convenient and conducive to most satisfactory results to apply it as a coating, and'in Fig. 2 I have shown' (diagrammatically only) the method of preparation as if it werea continuous process, although that need not be dicated by the diagrammatic showing at '1 of abrush coating machine, this material is coated ing of a drier at 9, and printed on the coated face,

with a finely divided pigment of a relatively high refractive index. Titanium o xide is highly desirable. Also mixtures of titanium oxide with either barium sulphate or calcium carbonate, both commercially known as titanox, or zinc oxide may successfully be used. The pigment is applied bymeans of a suitable vehicle, convenientlya casein size. Such size, moreovenhas the advantage of having a refractive index substantially different from that of the pigment itself.` The coating may be dried, as indicated by the diagrammatic showthe printing couple being indicated diagrammatically at 11. The printed web may then be waxed `by immersion inthe bath 13 of melted paraflin in the usual manner. Parafiin is thus applied to both sides of the web,and while in the example of the invention now under discussion the coating on the exterior or printed side is mainly superficial, that en the inner side willrpenetrate the original paper aswell as provide s.l superilciall film. In

Fig. 3 I have indicated the web at 5, the coating at 15, the printed impression at 17, the outer coating 'trast to display adjacent colorings.

of paraflin at 19 and the inneicoating at 21, andv have indicated bythe stippling the distribution of the latter coating in the body 5 of paper.' It will be understood that the figure makes no pretense to dimensional verisimilitude.

Wrapping material prepared as described is unique in the art in its balance of weight, strength and 'opacity and as such is not only technically new but as a wrapper provides highly improved results hitherto unobtained and does away with drawbacks hitherto accepted as inevitable limita-l tions of a waxed wrapper. lThus a wrapper may be provided weighing as paper, that is, less wax, under 30 pounds per ream and having a Mullen test of at least 8 and thus adaptable mechanically and commercially for wrappingpurposes, yet characterized by a high gloss and effective conper may be applied by the usual wrapping machines and sealed inthe usual manner by localized interi'usion of the wax coating.

The results obtained depended to a considerable degree on opacity. One measurement of pacity is effected by means of a standard instrument known as Martens photometer which determines the specular transmission, i.e., the transmission of a beam of light directed perpendicularly to the paper. Such a measurement, however, may not completely represent the apparent opacity of .material to the eye when viewed by incident light, as in the case ofviewin a wrapper applied to a loaf of bread, since t e light 'reaching the eye is in that case to a considerable extent diffused light. I am aware, however, of no satisfactory andwell recognized means of comparing opacities in this sense. To provide the best available explanation of my invention, however, I have caused samples as actually manufactured under my supervision to be tested with a Martens photometer. In .the acc'mpanying figures this transmission is reported as optical density which is the logarithm of the reciprocaloi' the transmission. I'hus by way of example the ordinary unwaxed paper stock referred to had an opacity of 2.28 points and may be characterized as moderately opaque. When` waxed with 50% wax, the percentage being based on the raw weight of the paper, the opacity was 1.50 points and the waxed paper was quite transparent. The drop in opacity, it will be noted, was about 34%. The same stock coated with the titanox pigment, titanium oxide and barium sulphate, measured 3.07 to 3.08 points andv might be said to be very opaque.

When waxed the opacity was 2.704 to 2.82, and

while there was a loss of opacity the drop was only 8 .to 12% and the resulting material was).

, more opaque than the original stock. Similar figures might be given for the other pigments referred to. In the case of the materials manufactured by me prior to the filing of this appli- .cation and having anopacity such that the chromatic effect of the wrapper was not substantially impaired when used on bread, the opacity as 'determined by specular on as above described was 2 points -ormore and in those samples which I considered most desirable 2.25 points or more..

My understanding of the theoretical considerations involved, which is borne out by actual experience, is that the material tobe associated with the paper, by'coating or otherwise, should be one with a high refractive index and finely di- .v vided. As the particle -I sire oi a pigment de- 4 creases, thev reflecting surface per unit volume sise ofthe pigment bev increases until thel grain comes so small that the grain no longeracts as a true reflector.- This -latter condition, however, is not likely to be encountered in the ranges of particle sizes available commercially and in the practical fleld it might be said that the smaller the particle size, the better the results from an opacity standpoint. The materials specifically referred to above as utilized by us have an average particle size by surface mean of about from .4 to .6 of a micron. Within the commercial range of pigments as I have studied them it appears, subject to such qualification as above indicated, that the opacity after waxing varies substantially as the refractive index. From a pigment of reasonably flne subdivision having a refractive index of 1.80 or higher relative to air good results ,may be expected. As suggested, titanium oxide, so-called titanox, and zinc oxide are commercially available pigments which are effective. The refractive indices of these relative to air are respectively 2.55, 1.90 and 2.01. It`

is interesting to reduce these to a refractive index as against melted parailin. The values are then respectively 1.68, 1.2'7 and 1.34. It will thus be seen that a mixture of wax and such pigments would be anisotropic. By utilizing such materials as coatings with casein size as described, a waxed sheet may be prepared with a loss' of opacity due to waxing of less than 20%.

The coated paper preferably should not be calendered as this will result in a decrease in the opacity lof the coated and waxed product. This can probably best be explained as resulting from a pressing down of the pigment particles and the extrusion of any included air by the calendering operation! In Fig. 3 I have diagrammatically illustrated the probable optical effect. It will be seen that the coated layer 15 provides a stratum of high reflective capacity which reflects the light falling upon the object from the outside. I thus see the printed image at 17 in its full brilliancy. Assuming that the base 5 being saturated with parain is in itself substantially isotropic, nevertheless the layer 15 intercepts light from the interior so that the brown color of the enclosed bread is not seen to dim the general effect. The printed matter carried by this' coating is supported by the paper layer 5 so 4that it can be applied by the wrapping operation to the bread and is protected and its luster probably increased by' appearance of the wrapping as herein described Vis greatly enhancedas contrasted with the ordinary waxed wrapping.

The water resistance of such a sheet as described may be measured by determining the permeability to Water vapor. VThe sheet described permitted a loss of only 26% of the-amount of water lost through otherwise comparable ordinary waxed paper under the same conditions. It is' probable that this is due to a somewhat heavier layer of wax on the exterior and to the nature of such layer. A comparison ofthe wrapper described and an uncoated wrapper waxed under similar conditions shows a somewhat greater amount of paraiiin on the former both when directly measured and when determined by gravi,- metric methods, while a photomicrograph of a cross section of the paper indicates a substan- 80 face appears to lbe covered with a number of rsmall particles, crystals of no particular shape,

whereas the surface of the wrapper preparedv in accordance with the invention has the appearance of consisting of large, fiat, flake-like particles of wax which do not project beyond the surface. This difference may bc due to the thicker coat of wax in the latter instance. In any event this condition of the surface may be considered to account for the much higher surface gloss of the wrapper embodying the invention, obviously a most desirable characteristic. Obviously also the smoother the exposed surface, the less likely it is to pick up dirt. l

In paper prepared as described crease marks due to bending of the paper are-not conspicuous. Likewise on account of the reective stratum, 15 in the example of the invention shown, beneath the outermost layer of wax 19 any displacement of the wax beneath one of the folds where a seal ismade will not affect the appearance of the completed package. It also appears that in printing directly on the wrapper, as illustrated in Fig. 2, a somewhat heavier film of ink than in the ca se of ordinary paper can be carried without excessive oifset thereafter.

By wrapper in the annexed claims I refer to an article in sheet form of the nature of paper as dstinguished from cardboard and of such tenacity and free flexibility as to permit it to be folded about an article by handor by ordinary wrapping machinery to forman enclosing covering therefor substantially conforming to the shape of the enclosed article.

Thel invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, `and the present embodiment should therefore be considered in all respects as illustrative and not restrictive; reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

I claim:

,1. A moisture-resisting wrapping for commodities characterized by substantial opacity 125 throughout its area, high gloss and eective contrast to display adjacent colorings comprising a body of paper stock having associated therewith material of substantially different refractive properties and treated with colorless wax, the opacity of the wrapper being not substantially more than 25% less than when unwaxed.

2. A moisture-resisting wrapping for commodities characterized by substantial opacity throughout its area, high gloss and effective contrast' to display adjacent colorings comprising a body of paper stock having associated therewith material of substantially different 'refractive properties and treated with colorless wax,' the opacity of the wrapper be'ng not substantially 140 more than 20% less than when unwaxed.

3. A moisture-resisting wrapping for commodities characterized by substantial opacity throughout its area, high gloss and effective contrast to display adjacent colorings comprising a body of paper stock having associated therewith a finely divided pigment, the refractive index of which relatively to air is. substantially 1.80 or higher and treated. with colorless wax.

4. A moisture-resisting wrapping for comof similar stock, free of such material and unhigh/.gloss and effective contrast to display adja' -fcentcolorings comprising a body of paper stock waxed, exhibiting no loss greater than .25 points as determined'by Marten's photometer.

5. A moisture-resisting wrapping for commodities characterized byl substantial opacity,

` high gloss and effective contrast to display adjacent coloring comprising Aa body of paper stock having associated therewith substantially uniformly` throughout its area finely divided titanium oxide and treated with colorless wax.

6. A moisture-resisting wrapping for commodities characterized by substantial opacity, high gloss and effective contrast to display .adjacent coloring comprising a body of paperv stock having associated therewith substantially uniformly throughout dits area finely divided zinc oxide andy treated with colorless wax.

7. A moisture-resisting wrapping for commodities characterized by substantial opacity, high gloss and effective contrast to display adjacent coloring comprising a body of paper stock having associated therewith substantially uniformly throughout its area a mixture of finely divided titanox and treated with colorless wax.

8. A moisture-resisting wrapping for commodities characterized by substantial opacity, high gloss and effective contrast to display adjacent colorings comprising a body of paper stock having a relatively highly refractive superficial coating covering one side thereof, a wax film over said coating, said wrapping Weighing, less wax, not substantially more than 30 pounds per ream,

having a Mullen test of substantially 8 points orover and an opacity as measured by Marten's photometer of substantially 2. points or more.

9. A wrapping sheet embodying 'for strength a body of felted cellulose fibers, for moisture resistance and for sealing colorless wax exposed at and substantially coextensive with both faces of the sheet and for appearance and for the display of printed matter carried thereby a substantially coextensive intermediate illm of finely divided pigment having a relatively high refractive index, said wrapping weighing, less wax, not substantially morethan 30 pounds per ream, having a Mullen test of substantially 8 points or over and an opacity as measured byMartens photcmeter of substantially 2. points or more.

10. A wrapping sheet embodying fr strength a body of felted cellulose fibers, for moisture resistance and for sealing'colorless wax exposed at and substantially coextensive with both faces of the sheet andalso embodyingv a substantially coextensive intermediate film of llnely divided white pigment of relatively high refractive properties carrying inscriptions in colored ink, said wrapping weighing, less wax, not substantially more than 30 pounds per ream, having a Mullen testof substantially Suppoints or over and an opacity as measured by Marten's photometer of substantially 2. points or more.

11. A moisture-resisting, self-sealing, waxed paperwrapper for commodities characterized by associated therewith material of substantially different refractive properties, said wrapper weighing, less wax. not substantially more than30 pounds per ream, having a Mullen test of substantially 8 points or over and an opacity as measured by Marten's photometer of substantially 2. points or more.

12. A moisture-resisting, self-sealing, waxed paper wrapper for commodities characterized by high gloss and effective contrast to display adjacent colorings comprising a body of paper stock having associated therewith material of substantially different refractive properties, said wrapper presenting an exterior film of wax and being as a whole highly anisotropic throughout its area as determined by the property that crease marks in said exterior film are substantially unnoticeable.

13. A moisture-resisting, self-sealing, waxed paper wrapper for commodities comprising an uncalendered pigment-coated paper printed in colored ink on the pigment-coated side and waxed and being as a whole and throughout its area not substantially less opaque than the uncoated. unwaxed paper.

14. A moisture-resisting, self-sealing, waxed paper wrapper for commodities characterized by high gloss and effective contrast to display adjacent colorings having filmsof wax on either side thereof anda substantially coextensive intermediate stratum of such substantially differ- .ent refractive properties as to conceal in the wrapped package alteration in appearance due to redistribution of wax at the seals.

15. A moisture-resisting, self-sealing, waxed paper wrapper for commodities comprising a body 'of paper stock having associated therewith material of substantially different refractive properties, said Wrapper weighing, less wax, not substantially more than 30 pounds per ream, having a Mullen test of substantially 8 or more yand of such opacity throughout its area that its chromatic effect to the eye is not substantially impaired by the color of an enclosed commodity such as bread. I

16. A moisture-resisting waxed paper for wrapping commodities characterized by substantial opacity, high gloss and effective contrast to display adjacent coloring comprising a body of paper stock having associated therewith substantially uniformly throughout its area finely.-

divided opaque white pigment.

17. A moisture-resisting wrapping for com. Irnodities characterized by substantial opacity,

high gloss and effective contrast to display adjacent colorings comprising a body of paper stock having a relatively highly refractive superflcial coating covering one side thereof, a wax film over said coating, said wrapping weighing, less wax, not substantially more than 30 pounds per ream, having a Mullen test ofy substantially'B points or over and of such opacity throughout its area that its chromatic effect to the eye is not substantially impaired by the color of an enclosed commodity such as bread.

18. A wrapping sheet comprising a body of felted cellulose fibers havingassociatd therewith substantially uniformly throughout its area finely divided pigment having a relatively high throughout its area that its chromatic effect to the eye is not substantially impaired by the color of an enclosed commodity such as' bread.

,CARROLL B. wams.

DISCLAIMER 1,938,9219.0arroll B.Wilk'ins, Nashua, N. H. WAxED WRAPPER. Patent dated December 12, 1933. Disclaimer filed July 18, 1936, by the assignee, Nashua Gummed coated Paper Company. Y

l Hereby disclaims from the scope of cla' 16 all waxed papers, if such be com- Erehended by said claim in its present form, other'than those in which the igmcnt as an indexl of refraction relatively high when compared with those of cellu ose and paran.

\ [O ic'ial Gazette August 18,11.936.]V y 

